1. Field of the Invention
The present invention relates to a method of manufacturing semiconductor device such as DRAM, and a manufacturing apparatus which is suitably used for the manufacturing method. In particular, the present invention is suitably used for manufacturing DRAM capacitor electrode having uneven (rough) surface, and applied to manufacturing apparatus which is suitably used for the manufacturing method.
2. Description of the Related Art
According to high-integration design of DRAMs, transistors and capacitors which serve as constituent elements of the DRAMs have been designed to be more reduced in area every time the generation of the DRAMs is changed. With respect to the capacitors, a capacitance value of a predetermined value or more, for example about 25 fF, is required to maintain the resistance to soft errors. Therefore, recently, cubic design of the capacitor electrodes has being promoted with the increase of the surface area of electrodes of the capacitors. Hemispherical Grained Silicon (hereinafter referred to as "HSG-Si") is a representative example of solid electrodes, and it is expected as electrodes of high-integrated DRAM at the 64-Mbits DRAM and subsequent generations because it can approximately double the surface area.
FIGS. 1A to 1D show a method of manufacturing capacitor electrodes having HSG-Si.
As shown in FIG. 1A, an insulating film 2 is formed on a semiconductor substrate 1, and then a contact hole 3 is formed in the insulating film 2. Subsequently, a phosphorus-doped amorphous silicon film is formed, and then etched in a predetermined shape to form a capacitor electrode (lower electrode) 4. In this state, the surface of the capacitor electrode 4 is covered by a natural oxide film 5.
Subsequently, a rare hydrofluoric acid treatment is performed, and the natural oxide film 5 on the surface of the capacitor electrode 4 is removed to form a hydrogen-terminated clean silicon surface 6 as shown in FIG. 1B.
Thereafter, silane gas is blown under a high vacuum condition, and then a heat treatment is performed under a high vacuum atmosphere. These steps are performed in order to form HSG-Si 7 on the capacitor electrode 4 as shown in FIG. 1C.
Thereafter, a step of forming a capacitor insulation film and a step of forming a capacitor upper electrode are carried out to form a capacitor of the DRAM.
In a semiconductor device manufacturing factory, an apparatus for performing the rare hydrofluoric acid treatment and an apparatus for forming HSG-Si are isolatively disposed in a clean room.
FIG. 2 is a plan view showing a conventional layout example of these apparatuses. As shown in FIG. 2, the rare hydrofluoric acid treatment apparatus 12 and the HSG-Si forming apparatus 13 are isolatively disposed while each of them faces to the bay 11 of the clean room. The semiconductor substrate 15 is accommodated in a carrier cassette 16, and moved to the rare hydrofluoric acid apparatus 12 by means such as AGV (Automated Guided Vehicle: not shown in FIG. 2) or the like (1, 2). After the treatment in the rare hydrofluoric acid apparatus 12 is completed, the semiconductor substrate 15 is moved to the HSG-Si forming apparatus by means such as AGV or the like again (3, 4, 5) to form HSG-Si. After the treatment in the HSG-Si forming apparatus 13 is completed, then the semiconductor substrate 15 is moved to the next capacitor insulation film forming step (6, 7).
However, in the HSG-Si forming step of the above conventional semiconductor manufacturing process, reproducibility of the shape of HSG-Si is low, and there usually occurs a problem that HSG-Si 7 cannot be formed on the surface of the capacitor electrode 4 as shown in FIG. 1D. As a result, the capacitance value of the DRAM capacitor is reduced, so that there occurs such a critical problem that the manufacturing yield and reliability of the DRAMs are lowered.